<!DOCTYPE html>
<html>
<head>
    <style>
        body, html {
            height: 100%;
            margin: 0;
        }
        .container {
            height: 100%;
        }
        iframe {
            display: block;
            border: 0.5px solid gray;
            width: 99.99%;
            height: 99.99%;
        }
    </style>
    <script>
        addEventListener("load", () => {
            let iframe = document.getElementsByTagName("iframe")[0];
            let params = new URL(location.href).searchParams;
            let currentDepth = params.has("depth") ? parseInt(params.get("depth")) : 0;
            iframe.src = `self-referential-iframe.html?depth=${currentDepth + 1}`;
            top.postMessage(currentDepth, "*");
        }, false);
    </script>
</head>
<body>
    <div class="container">
    <div class="container">
    <div class="container">
        <iframe scrolling="no"></iframe>
    </div>
    </div>
    </div>
</body>
</html>